Optimizing innoDB Databases

Hello, I have read the innoDB-related FAQs, but after running an optimization, the size of my innoDB database increases substantially:
Size of original database: ~550KB
1st optimization: ~1,000KB
2nd optimization: ~1,500KB
The FAQ mentions that the DB size may increase “a little” in the case of optimization on innoDB, but it sort of seems the DB is being replicated every time optimization is carried out (note: I am not a database expert). Is this extent of increase usual, or could you otherwise cast light on what might be happening here ? Thank you !